News Story

May 27, 2015

Environment@Harvard

Climate Change and Plant Species

Elizabeth (Lizzie) Wolkovich grew up in rural New Hampshire, but her early excitement about science didn’t come from her backyard. It came from her television. “I used to love NOVA,” says Wolkovich, assistant professor of organismic and evolutionary biology, of the long-running PBS series. She particularly remembers an episode that profiled researchers at the Keck Observatory in Hawaii. “They were classic scientists—people running around with backpacks, poorly dressed, running up and down the stairs in the observatory and looking at the sky. I thought that looked awesome.” She always wanted, she says, a job where she could wear a backpack.

It’s now part of her uniform as a field ecologist, where her work focuses on the effect of climate change on various plant species. “What we’ve fundamentally done with climate change is altered how organisms experience time,” she says. Plants have longer growing seasons, animals have shifted their reproduction and hibernation schedules—all these critical facets of survival have been distorted. What does this mean for the future of these communities? “I don’t think we, as scientists, have the full set of theories and knowledge we need to predict that yet.”

Addressing that deficit requires data. As part of her postdoctoral work, Wolkovich pulled together historical observations on phenology—when plants bud and flower—to better understand the effect of climate change on both native and invasive species. Wolkovich and her research partners compiled datasets that tracked all of the species in a variety of sites—including author Henry David Thoreau’s recordings from Concord, Massachusetts in the 1860s—to create their own phenological database. They used it to confront a question fundamental to the ecology of climate change: as the seasons change, will invasive species compete more successfully than native plants?

Wolkovich’s hypothesis argued that, yes, invasive species might do better because their inherent flexibility makes them able to react more quickly to earlier seasons than native species. One of the most extreme examples of this ability came from Concord—in the last 150 years, they found, the average day that a native species begins to bloom hasn’t changed. Exotic species, though, according to their data, have started to flower more than a week earlier. “This was pretty consistent across North America,” says Wolkovich. “It would suggest that the exotics are getting a leg up in performance through climate change, and perhaps humans have made it easier to be an exotic species and invade a community,” says Wolkovich. “If we continue at this rate of warming, it may be hard to have the time and resources to manage how much exotic species will increase.”

At her lab, Wolkovich is now trying to figure out the impact of that growth on plant communities. “What does the trend in climate—where we’re shifting spring forward—mean to coexistence?” says Wolkovich. “What does it mean to the types of communities that we’ll have in the future?”